Recently, there has been a trend to provide small-sized mobile electronic devices with one or more loudspeakers so as to allow for the output of audio signals, e.g. music stored in a digital format. One example of such mobile electronic devices is a mobile phone equipped with an audio player functionality. By providing the mobile electronic device with at least one loudspeaker, it becomes possible to output an audio signal not only via externally connected output devices, such as earphones, but also directly from the mobile electronic device.
However, in small-sized mobile electronic devices there exist difficulties in obtaining a good output sound quality. This is due to the fact that in these small-sized mobile electronic device it is typically not possible to provide the loudspeaker with a sufficient resonance volume as the volume available in a housing of the mobile electronic device is limited. Typically, this results in a low sound pressure and sensitivity of the loudspeaker in the region of bass frequencies.